Maurice ratel



, M. RATEL. AUTOMATIC STOKER OF THE UNDERFEED TYPE.

APPLICATION FILED FEB. 17, 1922.

Reissued Sept. 26

M. RATEL' AUTOMATIC STOKER OF THE UNDERFEED TYPE. APPLICATION FILED FEB.H, 1922.

Reissued Sept. 26, 1922. Q 1 5 4 62 2 SHEET $SHEET 2.

Reiasued Sept. 26, 1922.

' UNITED s ATEs summon RATEL, or NEW Yoax, N. Y.

\ 'UTOMATIC STOKER OF THE UNDERFEED TYPE.

Original application filed March 30, 1914, Serial No. 828,423. Dividedand'application filed October 5,

1920, Serial No. 414,836. Original No; 1,389,982, dated. September 6,1921. Application for reissue filed February 17, 1922. Serial No.-537,303.

lowlng specification.

This invention relates to automatic stokers and, more particularly, toautomatic stokers of the underfeed type, and it has for its object toprovide an improved device-of this character. which overcomes theserious defects and disadvantages inherent in automatic underfeedstokers heretofore employed.

It has heretofore been proposed to provide an automatic underfeed stokercomprising a series of alternating fuel retorts or troughs anddownwardly-inclined twyers, together with means in each of said retortsfor feeding fuel therethrough to the fuel bed. The stokers of this typeheretofore suggested, however, have been more orless de ective becausetheir fuel supporting. surfaces have been steeply inclined, generally atan angle of about sothat the feeding of the fuel and solid products ofcombustion would be effected to a largeextent, if not entirely, by

,the force of gravity.

In the first place, a stoker of this type requires a relatively largespace in a vertical direction and, therefore, is inapplicable to manyfurnace installations where it is impossible to raise the boilers orlower the boiler-room floor.

In the second place, a stoker of this type provides a bad dlstributionof fuel and, consequently, an imperfect combustion thereof owing to theunequal supply of air to different arts of the fuel bed. As gravity hasbeen re ied upon to effect feeding of the fuel and solid products ofcombustion, the fuel bed has taken a shape conforming at one side to thefuel-supporting surfaces and at its opposite side to the angle of reposeof the fuel and solid products of combustion which is an angle of ormore with ordinary fuels. This difference in the inclination between thefuel supporting surfaces of the stoker and the natural angle of reposeof the fuel has therefore resulted in a fuel bed which varies greatly inthickness from top to bottom, being relatively thin opposite the Y.,have in-' without combustion,

uppermost portion of the twyers, relatively thlck opposite theintermediate. portion of the twyers and relatively thin opposite thelowermost ortion of the twyers. This uneven distri ution of the fuel hasbeen accompanied by an equally uneven distributlon of the air. The air,tending to follow the lines of least resistance, has passed in excessthrough the thinner portions of the fuel bed and in insufficientquantities through the thicker portions of the fuel bed. Consequently,this insufficient supply of air at "the thicker portions of the fuel bedhas resulted in incomplete combustion and the formation of carbonmonoxid which escapes owing to the inadequate ill supply, and with aconsequent loss of cat.

In the third place, the ashes and fuel tend to fuse, forming largelumps, which in turn tend to takea steeper angle than the normal angleof repose of the fuel, until, becoming detached, they produce a suddenmovement of the fuel and solid products of combustion in the nature ofan avalanche, which carries with it both fuel and solid products ofcombustion onto the dumping sections of the stoker. Here the unburnedfuel is smothered in the ashes and slag and is carried into the ash pitand lost.

It has also been proposed to provide an automatic underfeed stoker ofthe above type with fuel-feeding members at both the top and the bottomof each fuel retort or trough. Devices of this type, however, have notovercome the difliculties arising from the fuel tending to take itsnatural angle of reose while, on the other hand, the lower uel-feedingmember has pushed much unburned fuel from the retort, where no provisionhas been made for supplying the same with sufiicient air to insureproper combustion, directly onto the dumpin sections of the stoker,where it is smothere in the ashes and slag and becomes extinguished andlost. In fact, considerable fuel that has become well ignited whileopposite the twyers is pushed onto the dumpin sections of the stokerand, becoming smot ered in the ashes and slag, also is extinguished andlost. On the other hand, this repeated feeding of incandescent fuel ontothe dumping sections of the stoker results in their early destruction byburning them out,

It is an object of the present invention to overcome these defects anddisadvantages by causing a continuous and regular advancing movement ofthe fuel and solid products of combustion in the fuel bed and feedingprogressively decreasing quantities offuel to the successive portionsfrom top to bottom of said bed, so as to provide proper distribution ofthe fuel and air in said bed and maintain the latter of substantiallyuniform thickness.

Another object of this invention is to provide, in combination withfuel-feeding means of the underfeed type, means at the rear of the fuelretorts or troughs, at the rear of the twyers, or both, whereby the fuelfed from the bottom of the retorts and distributed to the rear of thetwyers will be supplied with sufficient air to insure its combustion.

A further object of this invention is to provide in combination withfuel-feeding means of the underfeed type, a receiving grate at the rearof the series of twyers and fuel retorts or troughs which is providedwith an air supply decreasing progressively in the direction of the feedof the fuel, whereby unburned fuel reaching, said grate may be properlysupplied with air to support combustion, and which is also provided, ifdesired, with means for the injection of moisture at the rear of saidgrate whereby the solid products of combustion may be effectively cooledbefore reachin the dumping sections of the stoker and die heat conservedin forming combustible gases.

A further object of this invention is to provide, in combination withfuel-feeding means of the underfeed type, a receiving grate at the rearof the series of twyers and fuel retorts or troughs which comprises aplurality of movable grate bars that act in the nature of a sifter andfacilitate a regular advancing movement of the fuel bed.

Another object of this invention is to obviate the difiicultiesheretofore experienced from the rapi burning of the twyers by soconstructing them that they may be effectively cooled.

A further object of the invention is to provide, in combination with anautomatic underfeed stoker of the type referred to, means forsimultaneously varying the rate at which the fuel and air are suppliedthereto.

()ther objects relate" to the provision of anautomatic underfeed stokerwhich is simple in construction, efficient in operation,

inexpensive to maintain, and economical in its use of fuel. I

Broadly stated, the invention comprises an automatic underfeed stokerhaving a series of alternating twyers and fuel retorts or troughsproviding an inclined fuel bed whereby the fuel and solid rodll??? tcombustion are fed ddwnwardly with the aid of gravity, and a pluralityof fuel feeding members which as respects one feature of my inventionhave progressively decreasing capacity, disposed throughout the majorportion of the length of each retort, said fuel feeding members beingoperatively connected with the main power shaft of the stoker, so as tofeed progressively smaller or decreasing quantities of fuel to the fuelbed in substantially parallel directions. This progressive decrease inthe capacity of the successive fuel-feeding mem here may be effected byrendering said fuelfeeding members of progressively decreasing stroke,or progressively decreasing size, or both. Said fuel-feeding memberspreferably afford supports for the fresh fuel, and thereby insure itscontinuous and progressive distribution to the fuel bed throughout themajor portion of the length of each retort and also by their movement,produce an gndulatory or wave-like motion in said fuel The invention iscapable of receiving a variety of mechanical expressions, some of whichare shown on the accompanying drawings, but it is to be expresslyunderstood that the drawings are for purposes of illustration only andare not to be'construed as a definition of the limits of the invention,reference being had to the appended claims for that purpose.

In said drawings:

Figure 1 is a longitudinal section through an automatic underfeed stokerembodying the present invention;

Fig. 2 is a longitudinal section through another automatic underfeedstoker embodying the present invention; Fig. 3 is a partial plan toillustrate the disposition of apertures at the rear of the twyer-s andin the bottom of the fuel retorts or troughs, the twyers and retortsbeing shown diagrammatically, with the main and secondary fuel feedingmembers, grate bars and dumping plate omitted;

Fig. 4. is an enlarged horizontal section of one construction of twyerwhich embodies the present invention;

Fig. 5 is an enlarged horizontalsection of another construction of twyerwhich also embodies the present invention;

Fig. 6 is a side view of another construction of twyer which alsoembodies the present invention;

Fig. 7 is a face view of the twyer of Fig. 6;

Fig. 8 is a horizontal section ,on the line 88 of Fig. 6;

Fig. 9 is a side view of a twyer built up of a plurality of separatebars;

Fig. 10 is a face view of the twyer of Fig. 9,; and

; Fig. 11 is a schematic view of means for 4 connected to the secondaryfuel-feeding.

automatically and simultaneously controlling the speed of the stoker andthe admission of air.

The present invention is applicable to a wide variety of boilers andforms 'of furnaces and, therefore, as it is not limited to anyparticular type of boiler or furnace construction, the details of thelatter have not been illustrated.

In the form shown in Fig. 1, the automatic stoker consists of a seriesof alternating fuel retorts or troughs l and downwardly-inclined twyers2 of any suitable construction. Said twyers accordingly providedownwardly-inclined fuel-supporting surfaces whereby the advancingmovement of thefuel bed is effected with the aid of gravity. The fuel isfed through each retort or trough 1 from a hopper 3 by a plurality offuelfeeding members which, in'conformity with the present invention, areof progressively decreasing capacity and disposed throughout the majorportion of the length of said retort. In the form shown in Fig. 1, thefuel-feeding members comprise a main fuelfeeding ram or piston at and aplurality of secondary fuel-pushing members 5. The main fuel-feedingmember 4 may be reciprocated in any suitable way, as by a crank 6rotated by a shaft -7. The connecting rod 8 from said crank to themember 4 is shown as a bell crank lever to the depending end 9 of whichis pivotally' connected a rod 10 having its opposite end pivotallymounted at 11. are operatively connected to said rod 10 and saidconnecting rods are in turn operatively members 5. As the rod 10 isstationarily pivoted at one end and has'a range of movement at itsopposite end equal to that of the main fuel-feeding member 4, each ofthe succeeding secondary fuel-feeding members 5 has a proportionatelydecreasing range of movement, whereby said members are of successivelydecreasing capacity and adapted to feed progressively smaller quantitiesof fuel to the fuel bed. It is to be expressly understood. ,however,that any other suitable means for effecting a proportionate decrease inthe stroke of capacity of the successive fuel-feeding members may beemployed, if desired. Any suitable anti-friction means may also beemployed to facilitate the movement of said fuel-feeding members.

As the plurality of: fuel-feeding members are disposed substantiallthroughout the length of each fuel retort or trough and,

have substantially parallel movement in a 23 in any suitable way, asthrough the belthorizontal direction, they operate to agitate the entirefuel bed, giving the same a waving motion as the reciprocatingfuelpushers advance and recede. This agitation, aided by ravity, effectsa continuous and uniform 'sett ing movement of the fuel down the in- Aplurality of connecting rods 12 tend to effect an accumulation of fuelad jacent the bottom of the incline and a diminishing thickness of thefuel toward the top thereof. On the other hand, the fuel is fed throughthe retorts or troughs in progressively decreasing quantities from thetop to the bottom thereof and this supply of fuel is in inverseproportion to the thickness of the bed effected by said settlingmovement. Therefore the resultant of the progressively decreasing feedof the fuel from top to bottom of each retort and the agitation of theentire fuel bed is to obtain a fuel bed of substantially uniformthickness, whence arises a proper distribution of fuel and air and asubstantially uniform combustion. This .continous agitation has thefurther advantage of breaking up the of combustion down the slope iseffectively prevented. 1

Air is supplied the twyers in any suitable way, as through an air box 16communicat ing with a pipe 17 which may lead from any suitable blower orother air supplying devices.

At the rear of the series of twyers and fuel retorts or troughs is areceiving grate, shown as composed of a plurality of movable bars 18 ofany suitable construction, the same preferably having movement in thesame plane and transversely to said twyers and retorts, and desirablyalternate bars move in opposite directions. Said grate bars 18 may beactuated in any suitable way, as by cams 19 rotated by a shaft 20 driventhrough beveled gears 21 and belt or chain drive 22 from the main shaft23. Said grate bars '18 preferably have an air supply which is decreasedprogressively from front to rear in any suitable way, asdiagrammatically illustrated by the size of the air passages 24 in saidbars. In the rear bar or ,bars this-air supply ma be replaced by a steamor other wet fluid injection, so that the moisture when coming'incontact with the heated clinkers will form=combustible gases while, atthe same time, cooling the solid products of combustion.

In the rear of the grate afl'orded byv said bars 18 is'a fixed ortiltable dumping plate 25 for discharging the solid products ofcombustion into the ash pit 26.

The shaft 7 may be rotated from shaft or chain drive 27 andspeed-reducing mechanism of any suitable construction in the housing,28. e

In the form shown in Fi 2, the fuel feeding mechanism takes the cm of amain fuel-feeding member or ram 28 and a plurality of secondary,wedge-shaped fuel-feeding members 29 of progressively decreasing sizeand mounted on a connecting rod 30 operatively connected to the mainfuel-feeding member 28'. Said fuel-feeding members 28 and 29 have areciprocating movement par allel to the bottom 31 of the retort 1, buteach of the fuel-feeding members has a substantially verticalfuel-pushing face andeach of the secondary fuel-feeding members hasasubstantially horizontal fuel-supporting face, as do the fuel-feedingmembers in the embodiment of Fig. 1. It will therefore be perceived thatsaid fuel-feeding members .in the embodiment of Fig. 2 are ofprogressively decreasing capacity and disposed substantially throughoutthe length of each retort, whereby, as in the embodiment of Fig. 1, theyfeed the fuel by substantially parallel motion and in horizontaldirections to the successive portions of the fuel bed and, by

keeping the entire fuel bed in agitation and by feeding progressivelysmaller quantities of fuel from the top to the bottom of each retortmaintain a fuel bed of substantially uniform thickness. Otherwise, theconstruction of the stoker in the embodiment of Fig. 2 is, or may besubstantially .the same as that shown in Fig. 1. V

In conformity with this invention the fuel being fed through the bottomof the retorts or troughs is supplied with suflicient air to insure itsignition. To this end the bottom plate 34 at the rear of each retort ispreferably provided with one or more apertures 35 for the passage of airto thefuel, and each of the'twyers may also be provided with anextension plate 36 at its rear in which are provided one or moreapertures 37 for the passage of air. Instead of using apertures in theplates 34 and 36, however, suitable grate bars may be employed at. therear rtions of the fuel retorts and the extensions of the twyers. Thisauxiliary supply of air I their surfaces are .maintained relatively0001. To this end they may be "rovided interiorly with partitions 38forirecting the incoming air into cooling contact with their upperorfuel-supporting surfaces 39. before it escapes through the lateralapertures 40, as shown in Figure 4, or in addition they may havecorrugated walls 41 to increase their cooling surface, as shown in Fig.5..

lation of the speed. A chan with this inventionthe mass M additlonaladvantage that the twyers are formed with external recesses 42 in whichthe ashes may collect and form a protective layer.

The twyers vmay also be provided with apertures 43 in their upper orfuel-support- The revision of corrugations also has the ing faces, aswell as with the lateral aper tures 40, as'shown in Figs. 8 to 10, sothat the entire surface of the twyers may be cooled by the passage ofair therethrough.

This constructionhas the further advantage that the fuel-supportingsurface of 7 each twyer also functions as a grate so as to considerablyincrease the combustion rate without increasing the air pressure, or tomain tain the same combustion rate witha smaller a1r pressure or evenenabling the stoker to I work with natural draft Said twyers may beeither of unitary construction as'shown in Fi 6, 7 and 8, or they may bebuilt up of a p urality of separate bars H as shown in Figs. 9 and 10,in which event the separate bars may be held together in any suitable 11 is to be expremly understood that the grate bars may be of anysuitable cross section, as round, triangular, etc., and the aperturestherein may be of any suitable shape and of the same or varying section.Furthermore, any and all of these provisions for cooling the twyers maybe combined with means for cooling the same through the use of a steamjet, humid air, water spray, circulation of w er, etc.

Any suitable means may be.provided for supplying air, driving the Stokerand varying the speed of said mechanism. When a l steam engine or directcurrent motor is employed the speed may bevaried automatically orotherwise in any suitable way, as by automatically-controlled valves oran auto-' matically-controlled rheostat. When an alternating current isused and especially when a three-phase current is employed, so that onlslight variations of speed may be obtained by variations of the current,

change-speed devices of any suitable construction may be applied to theair-supplying mechanism and the stokers and also individually to eachstoker to secure a proper reguapplication to each individual stoker isshown diagrammatically in Fig. 11, wherein 45 is the change-speed box,46 a gear driven in, any suitable way from the main shaft 23, and 47 aclutch of any suitable construe tion for connectin the gear 46' with thedriving shaft of t e change-speed mechanism.1n the box 45, said clutchbeing normally pressed into operative position by the speed box forspring 54:. The change-speed mechanism is shown as controlled by a'lever49 having a handle 50 which controls a catch for engagement with theteethbl of the sector ,varied in conformity wit plate 52. Said lever 49may have an extension 53 for engagement with the arm 53" of the bellcrank 55, which in turn controls the movement of the clutch 47 intoandout of operative position.

It is also desirable -thatthe mechanism for changing the speed of theStoker be connected to the means for controlling the supply of air tothe furnace, so as to maintain a constant relation between the quantityof fuel and the quantit of air admitted thereto. This is accomplished inthe structure diagrammatically illustrated in Fig. 11 by the connectionof the damper 56 in the air-supplying conduit with the lever 49 of thespeed-regulating device by a cable 57 a counter-Weight 58 being shown ascon nected to the arm 59 of the damper 56 to facilitate adjustment ofthe latter.

It is to be expressly understood that the term capacity as employed inthe claims with reference to the fuel feeding members is to be construedas generic to fuel feeding members of successively decreasing feedingcapacity whether effected by pro-' gressive decrease in size, stroke, orotherwise. While the constructions shown on the drawings have beendescribed with considerable particularity it is to be expresslyunderstood that the invention is not limited thereto, as the same iscapable of being embodied in a variety of forms. Inplace of the crankmechanism shown for driving the fuel-feeding members any other suitabledevices may be employed' The num-- her, size, form, and inclination ofthe twyers and fuel retorts or trou hs may also be the fuel to beemployed. Certain features of the invention may be emplo edwithout otherfeatures thereof, and clianges may be made in details of construction,proportion and arrangement of parts without departing from the spirit ofthis invention. Reference is therefore to be had to the claims heretoappended for a definition of said invention. This a plication is for thereissue of my Patent o. 1,389,982, granted as a division on myapplication Serial No. 828,423, filed March 30,1914, which has maturedinto Patent No. 1,366,098, dated Jan. 18, 1921, and which in turn is adivision of my application Sr. No. 7 57,353, filed Mar. 28, 1913.

What is claimed is:

1. In an automatic underfeed stoker, a series of alternating twyers andfuel retorts ,or troughs providing an inclined fuel bed whereby the fueland solid products of combustion. are fed downwardly with the aid ofgravity, and means for feeding fuel through said retorts to said fuelbed comprising amain fuel-feeding member and a plurality of secondaryfuel-feeding members dis osed substantially throughout the lengthvo eachretort, the successive memaid of gravity, and means for feeding fuelthrough said retorts to said fuel bed comprising a main fuel-feedingmember and a plurality of secondary fuel-feeding members disposedsubstantially throughout the length of each retort, thelsuccessivemembers in each retort having progressively decreasing capacit in thedirection of inclination of the uel bed and substantially simultaneousand parallel movement in the same direction to feed progressivelysmaller quantities of fuel to the fuel bed.

3. In an automatic underfeed stoker, a series of alternating twyers and.fuel retorts or troughs providing an inclined fuel bed whereby the fueland solid products of combustion are fed downwardly with the aid ofgravity, and means for feeding quantities of fuel through said retortsto said fuel bed in substantially arallel directions and comprising amain ber and a plurality of secondary fuel-feedin and fuel supportingmembers disposed su stantially throughout the length of each retort, themembers in each retort having substantially parallel reciprocatingmotion and being of progressively decreasing capacity from the top tothe bottom of the retort.

4. In anautomatic underfeed stoker, a series of alternating fuel retortsor troughs and downwardly-inclined twyers; and means uel-feeding memforfeeding fuel through said retorts comprogressively smaller quantities tothe fuel 5.'In an automatic underfeed stoker, a series of alternatingfuel-retorts or troughs and downwardly-inclined twyers, and means forfeeding fuel through said retorts comprising a main fuel-feeding memberattl e' upper end of secondary fuel-feeding members disposed throughoutthe major portion of the length of each retort and having pro ressivelydecreasing capacity, said fueleedlng members in each retort constitutingsupports for each retort and a plurality of the fuel and havingsubstantially parallel movement in the same direction tofeedprogressively smaller quantities to the fuel bed.

6. In an automatic underfeed stoker, .a series of alternating fuelretorts or troughs and downwardly-inclined twyers prov-id mg adownwardlyinclined fuel bed, and means for feedin quantities of fuel insubstantially parallel irections through said retorts to said fuel bedand comprising a main fuelfeeding member at the upper end of each retortand a plurality of secondary fuel-feeding members disposed throughoutthe major portion of the length of each retort, the members in eachretort having substantiallyparallel motion of v progressively decreasingstroke.

7. In an automatic underfeed stoker, a series of alternating fuelretorts or troughs and downwardly-inclined twyers providing a downwardlyinclined fuel bed, and means for feeding quantities of fuel insubstantially parallel directions through said retorts to said fuel bedand comprising a main fuelfeeding member at the upper end of each retortand a plurality of secondary fuelfeeding members disposed throughout themajor portion of the length of each retort,

the members in each retort being of progressively-decreasing capacityand having substantially parallel motion.

8. In an automatic underfeed stoker, a

- series of alternating fuel retorts or troughs and downwardly-inclinedtwyers, and means for feeding fuel through each of said retortscomprising a main fuel-feeding memher, a rod operatively connected tosaid main fuel-feeding member and pivotally mounted at :its oppositeend,'and a plurality of secondary fuel-feeding members operativelyconnected to said rod and moved progressivelydecreasing amounts.

9. In an automatic underfeed stoker, a seriesof alternating fuel retortsor troughs and downwardly-inclined twyers providing a downwardlyinclined fuel bed, and means a for feeding quantities of fuel insubstantially parallel directions through each of said retorts to saidfuel bed and comprising a main fuel-feedingmgmber and a pluralitv ofsecondary fuel-feeding members operatively connectd to saidmainfuel-feeding member and having substantially horizontal up er faces and"substantially vertical fuel-pushing faces, said members havinprogressively decreased capacity to. [fee 10. In an automatic underfeedstoker, a

series of alternating fuel retorts or troughs and twyers providinganinclined fuel bed wherebythe fuel andisolid products of com bustion arefed downwardly with the aid of gravity, and means for'feeding fuelthrough 1 said retorts to said fuel bed comprising a main fuel-feedingmember and a plurality of progresslvely a smaller quantities of-fuel tothe fuel bed.

secondary fuel-feeding members disposed throu bout a major portion ofthe length of eac retort, said fuel feedin members in each retort havingprogressive y-iiecreasing capacity and substantially parallel andsimultaneous feeding motion in the same direction. Q a

11. In an automatic underfeed stoker, .a

series of alternating fuel retorts or trou hs and twyers providing aninclined fuel ed vwhereby the fuel and solid products of combustion arefed downwardly with the aid of gravity, and means for feeding fuelthrough said retorts to said fuel bed comprisin a main fuel-feedingmember and a p'luarfity of secondary fuel-feeding members disposedsubstantially throughout the length of each retort, said members havingprogressively decreasing capacity and successively adapted to feedprogressively smaller quantities .of

fuel to, the fuel bed in substantially parallel directions.

12. In an automatic underfeed stoker, a series of alternating fuelretorts or troughs and downwardly-inclined twyeis providin an inclinedfuel bed whereby the fuel an solid products of combustion arefeddownwardly with the aid of gravity, and a plurality of fuel-feedingmembers in each of said retorts disposed substantially throughout thelength of each retort, said members having progressively decreasingcapacity and respectively adapted to feed the fuel toward successiveportions of said fuel bed in substantially parallel directions.

series of alternating fuel retorts or troughs and downwardl -inclinedtwyers providing an inclined fue bed whereby the fuel and solid productsof combustion are fed downwardly with the aid of gravity, and aplurality of fuel-feeding members in each of said retorts adapted tofeed the fuel in sub- 13. In an automatic underfeed stoker, a

stantially parallel directions toward successive portions of saidfuelbed and agitate the same to aid gravity in the movement of the fueland solid products of" combustion down the incline of said bed, saidfuel-feeding members havin progressively decreasing capacity to fee fuelto said bed in inverse proportion to the thickness of the bed. arisingfrom gravitational movement of the fuel and solid products ofcombustion.

14. In an automatic underfeed stoker, a seriesof alternating fuelretorts or troughs and downwardl. -inclined twyers providin an inclinedfue bed whereby the fuel and solid products of combustion are feddownwardly with the aid of gravity,- and a plurality of fuel-feedingmembers in each of said retorts disposed throughout the major portion ofthe length of each retort and adapted to agitate substantially theentire fuel bed to aid gravity in the downward movement of the fuel andsolid products of gravity, and means for feeding uel in substantiallyparal combustion, said fuel-feeding" members having pro essivelydecreasing capacity to supply fue in substantially parallel dlrectionsto said bed in inverse proportion to the thickness of said bed arisingfrom gravitational movement of the fuel and solid products ofcombustion. U

15; In an automatic underfeed stoker, a series of alternating twyers andfuel retorts or troughs providin an inclined fuel bed whereby the fuelan solid products of combustion are fed downwardly with the aid ofquantities of el directions through said retorts to said fuel bed andcomprising a plurality of fuel-feeding members having progressivelydecreasing capacity in each of said retorts and successively adapted tofeed progressively smaller quantities of fuel to the fuel bed, the rearend of each of said retorts bein provided in its bottom with aperturesfor t e passage of air.

16. In an automatic underfeed stoker, a series of alternating twyers andfuel retorts or troughs providin an inclined fuel bed whereby the fuelan solid products of combustion are fed downwardly with the aid ofgravity, each of said twyers having an extension at its rear endprovided with an, aperture for the passage of air, and means 'for'feeding fuel through said retorts oomprisin a plurality of fuel-feedingmembers in eae of said retorts, said members having a pro essivelydecreasing capacity and successively adapted to feed progressivelysmaller quantities of fuel to the fuel bed in substantially paralleldirections.

17. In an automatic underfeed stoker, a

- plurality of alternating tw ers and fuel reed to feed tortsor'troughs, means or feeding fuel through said retorts comprising aplurality of fuel-feeding members successively adaptro ressively smallerquantities.- of fuel to t e uel bed, and a grate at the rear of saidretorts andtwyers provided with an air suppl decreasing progressively inthe direction 0 the travel of the fuel.

18. In an automatic. underfeed stoker, a

plurality of alternating tw ers and fuel retorts or troughs, means orfeeding fuel through said retorts comprising a plurality of fuel-feedingmembers successively adapt ed to feed pro ressively smaller quantitiesof fuel to the uel bed, a plurality of movable grate bars at the rear ofsaid retorts and twyers,-and means at the rear of said grate bars fordumping the solid products of combustion.

19. In an automatic underfeed stoker, i1

plurality of alternating tw ers andfuel retorts or troughs, means orfeeding fuel through said retorts comprising a lurality of fuel feedingmembers successive y "adapted to feed progressively smaller quantitiesof fuel to the fuel bed, and a plurality of reciprocating grate bars atthe rear of said retorts and twyers and movable transversely of thesame.

20. In an automatic underfeed stoker, a plurality of alternating twyersand fuel retorts or troughs, means for feeding fuel through said retortscomprising a plurality of fuel-feeding members successively adapted tofeed progressively smaller quantities of fuel to the fuel bed, and aplurality of reciprocating grate barsat the rear of said retorts andtwyers, alternate grate b'ars having movement in reverse directions.

21. In an automatic underfeed stoker, a plurality of alternating twyersand fuel retorts or troughs, means for feeding fuel through said retortscomprising a plurality of fuel-feeding members successively adapted tofeedprogressively smaller quantities of fuel to the fuel bed, and aplurality of reciprocating grate bars at the rear of said retorts antwyers provided with an air supply decreasing progressively in thedirection of'the feed of the fuel, alternate grate bars having movementin reverse directions.

22. In an. automatic underfeed stoker, a plurality of alternating twyersand fuel retorts or troughs providing an inclined fuel bed whereby thefuel and solid products of combustion are fed downwardly with the aid ofgravity, said twyers having internal air-directing walls for directinair into cooling contact with the heate surface of the twyers, and meansfor feeding fuel through said retorts comprising a plurality offuel-feeding members in each of said retorts, said members havingproretorts or troughs providing an inclined fuel bed whereby the fueland solid products of combustion are fed downwardly with'the aid ofgravity, said twyers having corrugated walls and providing external ashcollecting recesses, and means for feeda ing fuel through said retortscomprising a plurality of fuel-feeding members in each of said retortssuccessively adapted to feed progressively smaller quantities of fuel tothe fuel bed in substantially parallel din'gctions.

"24. In an automat c underfeed stoker, a plurality of alternatin twyersand fuel retorts or troughs provi 'ng an inclined fuel bed whereby thefuel and solid products of combustion are fed downwardly with the aid ofgravity, said twyers being'provided with apertures for the passage ofair in both their up means forfeedmg fuel throu h said retortscomprising a plurality o fuel-feeding r and lateral faces, and p membersin each of said retorts, said members having progressively decreasingcapacity and successively adapted to feed. progressively smallerquantities of fuel to the fuel bed in substantially parallel directions.

25. In an automatic underfeed stoker, a plurality of alternating twyersand fuel retortsor troughs providing an inclined fuel 'progressivelysmaller quantities of fuel to the fuel bed in substantially paralleldi-.

rections.

26. In an automatic underfeed stoker, a

plurality-of alternating twyers and fuel retorts or troughs providing aninclined fuel bed whereby the fuel and solid products of combustion arefed downwardly with the aid of gravit said twyers being each composed ofa p urality of bars operatively related and constructed to be cooled bythe flow of air therethrough, and means for feeding fuel through saidretorts comprising a plurality of fuel-feeding members in each of saidretorts, said members having progressively decreasing capacity andsuccessively ada ted to feed progressively smaller quantities of fuel tothe fuel bed :in substantially parallel directions.

a 27. In an automatic underfeed stoker, a series of. alternating twyersand fuel retorts 'or troughs, means for feeding fuel through saidretorts comprising a plurality of fuel-- feeding members in each of saidretorts,

said members having progressively decreasing capacity and successivelyadapted to feed progressively smaller quantities of fuel to the fuelbed, means for regulating the supply of air, means for regulating thespeed of said stoker, and operative connec--.

tions between said last-named means whereby the supply of fuel and airmay be carried simultaneously. 1

28. In an automatlc underfeed stoker, a

series of alternating fuel retorts or troughs and downwardly inclinedtwyers providing an inclined fuel bed'whereby the fuel and solidproducts ofcombustion are-fed downwardlywith the aid of gravity, andmeansdisposed throughout the major portion of the length of said retortsfor feeding fuel through the same to said fuel bed, said meanscomprising a in members in e'ac retortconstituting substantiallyhorizontal. fuel supports.

29. In" an automatic underfee stoker, a

plurality of fuel-feed for the passage of air.

30. In an automatic underfeed stoker, a series of alternating fuelretorts or troughs and downwardly inclined twyers providlng an inclinedfuel bed whereby the fuel and solid products of combustion are fed downwardly yvith the aid of gravity, a stationary apertured plate extendlngfrom the lower end of each twyer, and means for feeding fresh fuelthrough said retorts to said fuel bed comprising a plurality of fuelfeeding members disposed substantially throughout the length of eachretort and having substantially horizontal fuel supporting sur- '90faces. a w i L 31. In anvautomatic underfeed stoker, a plurality ofalternating twyers and fuel retorts or troughs, means for, feeding'fuelthrough said retorts comprising a plurality of fuel-feeding memberssuccessively adapted to feed fresh fuel to the fuel bed, and

a grate at the rear of said retorts and twyers providedwith an airsupply decreasing pro-. gre'islvely in the directlon of travel of the32. In an automatic underfeed stoker, a plurality of alternating twyersand fuel retorts. or troughs, means for feeding fuel through saidretorts'to the fuel bed comprising aplurality of, fuel-feeding members,v a plurality of grate'bars at the rear of said retorts and twyers andmovable transversely of the same, and means at the rear of saidgratebars for dumping the solid products of combustion.

33 In an automatic stoker,a plurality of alternating twyers and fuelretorts or troughs, means for feeding fuel through said retorts to thefuel bed comprising a plurality of fuel-feeding members, and a pluralityof reciprocating grate bars at the rear'of said retorts and twyers andmovable r and a plurality of reciprocating grate bars at 35 the rear ofsaid retorts and twyers, alternate grate bars having movement in reversedirections. I I l substantially horizontal direction .10

35. In an automatic stoker, a plurality of alternating twyers and fuelretorts or troughs, means-,for feeding fuel through said retorts to thefuel bed comprising a plurality of fuel-feeding members, and a pluralityof reciprocating grate bars at the rear of said retorts and twyersprovided with an air supply decreasing progressively in the direction ofthe feed of the fuel, al-

ternate grate bars having movement in reverse directions.

36. In an automatic underfeed stoker, a plurality of alternating twyersand fuel retorts or troughs providing an inclined fuel bed whereby thefuel and solid products of combustion are fed downwardl with the aid ofgravity, said twyers hav1ng corrugated walls and providing externalashcollecting recesses, and means for feeding fuel through said retortscomprisin a plurality of fuel-feeding members in each of said retortsadapted tofeed the fresh fuel to the fuel bed in a substantiallyhorizontal direction.

37. In an automatic underfeed stoker, a series of alternating twyers andfuel retorts or troughs providing an inclined fuel bed whereby the fueland solid products of combustion arefed downwardly with the aid ofgravity, and means for feeding fuel through said retorts to saidinclined fuel bed in a substantially horizontal direction, said meanscomprising a main fuel feeding member and a pluralit of secondary fuelfeeding members dispose substantially throughout the length of eachretort, said secondary fuel feeding members having substantiallyhorizontal fuel supporting surfaces and substantially vertical fuelpushin faces.

'38. In an automatic under eed stoker, a series of alternating twyersand fuel retorts or troughs providing an inclined fuel bed whereby thefuel and solid products of combustion are fed downwardl with the aid ofgravity, and means for feeding fresh fuel through said retorts to saidinclined fuel bed in substantially horizontal and parallel directions,said means comprising a plurality of fuel feeding members in each retortdisposed throughout a major portion of the ength thereof and havingsubstantially horizontal fuel supporting surfaces and substantiallyvertical fuel pushing faces.

39. In an automatic underfeed stoker, a plurality of alternating twyersand retorts providing an inclined fuel bed down which the fuel and solidproducts of combustion move with the aid of gravity, and means forfeeding fuel through said retorts tosaid inclined fuel bed comprisingmain and secondary fuel feeding members disposed substantiallythroughout the length of each retort and having reciprocating motion,said secondary fuel feeding members having subportion of the len th ofeach retort and operatively connecte to said main fuel feeding member,said secondary fuel feedin members having substantially horizonta fuelsupporting surfaces and substantially vertical fuel pushing faces.

41. In a gravity underfeed stoker, a plurality of alternating twyers andretorts or troughs providing an inclined fuel bed, and

automatic means for feeding fuel through said retorts to said fuel bedcomprisinga plurality of reciprocating fuel feeding members disposedlongitudinally throughout the major portion of the length of each retortand having substantially horizontal fuel supporting surfaces andsubstantially vertical fuel pushing faces whereby fresh fuel is fed tosaid inclined fuel bed in a substantially horizontal direction.

42. In a gravity underfeed stoker, a plurality of alternating twyers andretorts or troughs providing an inclined fuel bed, and automatic meansfor feeding fuel through said retorts to said fuel bed comprising alurality of fuel feeding members disposed ongitudinally throughout themajor portion of the length of each retort and havlng reciprocatingmotion, said members bein provided with substantially horizontal fuesupporting faces and substantially vertical fuel pushing faces.

43. In an automatic underfeedstoker, a plurality of alternating twyersand retorts providing an inclined fuel bed, and means for feeding fuelthrough said retorts to said fuel bed in a substantially horizontaldirection comprising a plurality of fuel feeding members disposedthroughout the major portion of the length of each retort, said fuelfeeding members having successively step d relation and substantiallyhorizontal el supporting surfaces. 1

44. In an automatic underfeed stoker, a plurality of alternating twyersand retorts roviding an inclined fuel bed, and means 1n each retort forfeeding fresh fuel through said retorts to said fuel bed in asubstantially horizontal direction, said fuel feeding means extendinthrou bout the major portion of the lengt of eac retort and havingstepped formation and providing a plurality of horirelation. to providesubstantially horizontal fuel supporting surfaces and substantiallvertical .fuel pushing faces whereby fres fuel is fed to said inclinedfuel bed in sub stantially parallel and horizontal directions.

46. In an automatic underfeed stoker, a series of alternating fuelretorts or troughs and downwardly inclined twyers providing an inclinedfuel bed, and means for feeding fresh fuel through said retorts to saidfuel bed, said means-comprising a plurality of fuel feeding members ineach retort extending throughouta ma'or portion of the length thereofand arra to operate in the fresh fuel therein, said uel feeding membershaving successively stepped relation and substantially horizontal fuelsupporting surfaces.

47. In an automatic'underfeed stoker, a series of alternating twyers andfuel retorts or troughs roviding an inclined fuel bed,- means supp yingfuel to said fuel bed, and plates disposed between said twyers andforming with the latter extensions of said retorts, said plates beingprovided with apertures for the passage of air.

4 8. In an automatic underfeed stoker, a series of twyers and retortsrovidin inclined fuel bed, means forceding resh .fuel through saidretorts to said fuel'bed,

and plates disposed between said twyers and forming with the latterextensions of said retorts, said plates bein provided with apertures forthe passage 0 air.

49. In an automatic underfeed stoker, a

series of alternating twyers and retorts providing an inclined 'fuelbed, means for feed ing fuel through said retorts to said fuel bedcomprisingmain and seconda fuel feeding members isposed substantial ythroughout the length of each retort, and plates disposed between saidtwyers and forming. with the latter extensions of said retorts, saidplates being provided with apertures for the passa of air.

50. n an automatic underfeed stoker, a series of alternating twyers andfuel retorts or troughs providin an inclined fuel bed,

; means supplying fue to said fuel bed, plates 7 wit said plates beingprovided with apertures dis between said twyers and forming the latterextensions of said retorts,

, supply. an 1 for the passage of air, and plates at the bottom of saidtwyers provided with an air supply.

51. In an automatic underfeed stoker, an underfeedportion and anoverfeed portion, said underfeed portion comprising a series ofalternatin fuel retorts or troughs and downwardly inclined twyers andsaid over-'- feed portion comprising stationary apertured platesdisposed between the lower ends of said twyers and stationary aperturedplates extending rearwardly from the latter and means for feeding fuelto said overfeed and underfeed portions.

52. In a gravity underfeed stoker, a series of alternating twyers andretorts providing an inclined fuel bed, a plurality of reciprocatingfuel feeding devices in said retorts arranged to operate in the freshfuel therein, and plates disposed between said twyers and forming withthe latter extensions of saidretorts, said plates being provided withapertures for the passage of air.

53. In an automatic underfeed stoker, a series of alternating twyers andfuel retorts or troughs providing a fuel bed, means for feeding fuelthrough said retorts, and a grate at the end of said fuel bed providedwith a progressively decreasing air supply.

54. In an automatic underfeed stoker, a series of alternating twyers andretorts roviding an inclined uel bed, means for eedin fuel through saidretorts to said fuel be plates at the bottom of the fuel bed providedwith apertures for the passage of air, and grates receiving the fuel andsolid products of combustion from the fuel bed and having "aprogressively decreasing air 55. In an automatic underfeed stoker, a-

series of alternating tvivygrs and retorts proue viding an inclined d,said twyers su plying air to said fuel bed, and grates at t e bottom ofsaid fuel bed and having a progressively decreasing air supply.

56. In a gravity-underfeed stoker, the combination of a series ofretorts, and cor rugated twyers alternating therewith.

57, In a gravity-underfeed stoker, the combination of a series. ofreterts, and

twyers alternating therewith, said twyers being composed sections. v

58. In a gravity-underfeed stoker, the

combination of a series of retorts, and a series of corrugated-twyersprovided with openings for admitting a combustion-supporting fluid.through t e walls thereof.

a gravity underfeed d'oker, a series III of a series of corrugated ofalternating retorts and sectional twyers, I

the sections of said twyers having corrugated wallsprovided with:openings fora combustion supporting fluid. I

60. In a gravity underfeed stoker, the

combination of a series of alternating retorts and corrugated twyersfree from horizontal surfaces.

61. In an automatic underfeed stoker, a

5 plurality of alternating twyers and retorts providing an inclined fuelbed whereby the fuel and solid products of combustion are fed downwardlywith the aid of gravity,

means for feeding fuel through said retorts to said fuel bed, and meansproviding a proessively decreasing air supply for the fuel in itsdirection of travel.

In testimony whereof I have signed this specification.

MAURICE RATEL.

